In many oilfield operations, e.g., drilling, casing running, etc., a tubular is run into the wellbore. During run-in, the tubular is typically connected to, i.e., made-up to, one or more tubulars that have already been run-in, thus providing an end-on-end connection forming a tubular string. In some cases, elevators are employed to position the tubular above the wellbore, allowing the tubular to be made-up to the subjacent, already-run tubular. The elevator then supports the weight of the tubular string through its engagement with the tubular, and lowers the tubular into the wellbore.
There are several different types of elevators, which employ different structures to engage the tubular and support its weight. Generally, elevators either employ slips that engage the radial outside of the tubular, or a load bushing that catches an upset (e.g., a shoulder) of the tubular or a lift nubbin connected to the top of the tubular. Slip-type elevators generally use the weight of the tubular to provide the gripping force, and may include teeth or the like that bite into the tubular. Load bushing elevators, by contrast, provide a collar or landing surface upon which the upset bears.
Both types of elevators present challenges in deep sea or other applications where the tubular strings can become extremely heavy. With slip-type elevators, after making the tubular up to the string, the weight of the tubular can cause the slips to apply too great of a gripping force on the tubular, which can crush or otherwise damage the tubular. Further, in some applications, it may be advantageous or required to avoid marking the tubular. On the other hand, with load-bushing-type elevators, the upset of the tubular, e.g., where the tool joint is coupled with the pipe, may fail if the weight is too great. One solution is to form higher-grade tool joints that are designed to support the load; however, such higher-grade tool joints may result in higher make-up torques, which can present additional challenges.